The invention relates to a wobble joint fitting for an adjustment device of a motor vehicle seat, in particular for a backrest joint fitting, with a) a first fitting part comprising an internal ring gear, b) a toothed eccentric gear that engages this internal ring gear and that has an eccentric hole and a collar, c) an eccentric comprising a rotatable drive part, a control part and wedge segments, the control part comprising control surfaces that come to abut against the wedge segments, and d) a second fitting part that is adjustable with respect to the first fitting part.
Wobble fittings are disclosed in DE 10 2009 001 309 A1, DE 10 2005 054 489 B4, DE 10 2004 007 043 B2, DE 102 030 06 A1 and DE 15 80 541 A, for example. The wrap spring is supposed to provide a run-off protection. Though in principle, the wobble joint fitting is self-locking; there are, however certain loads during the driving operation or in other situations which lead to the wobble joint fitting automatically becoming displaced nevertheless. This is referred to as the fitting running off. A wrap spring is intended to counteract this.
A wobble joint fitting is known from DE 195 48 809 C1 which, for preventing run-off, comprises a blocking ring provided in the radial plane between the wedge segments and the control part and which comprises on its outer circumference at least one latching tooth which in the normal position engages a counter toothing of the toothed eccentric gear. It is elastically biased into the engagement position. It can be withdrawn from the engaging position by means of fittings of the drive part by the drive part being rotated. The engaging position is thus cancelled and the rotary movement of the wobble joint fitting is enabled.
This solution employs a relatively complicated component forming the blocking ring. Noise-free operation is not always achieved; a development of noise between at least one latching tooth and the counter toothing can virtually not be precluded. As a rule, there is a ratchet sound.